Stationary npcs

[MikeJeffers]

Based off branch: https://github.com/OpenPerpetuum/PerpetuumServer/pull/255 Merged AND https://github.com/OpenPerpetuum/PerpetuumServer/pull/263 Merged

The following changes are added in this PR:

• New NPC AI states exclusively for NPCs that cant move
• Updated bodypull logic to account for multiple player body pull aggro

• Primary target selection randomization and choice strategies

  NPC turrets and gamma turrets are expected to change primary targets at some interval. There are reasons not to focus based on one strategy or logic alone as players may "draw" aggro away from other players and take advantage of some blindspot. Turrets are not so much trying to kill targets as they are deter and keep targets at bay. This is why they should not simply inherit the threat-priority targeting of the base AI stack.

[MikeJeffers]

No worries @nref-dan I put it up as a draft so I could better monitor the diff, and try some other things locally, as this is all pretty fresh stuff in a pretty sensitive part of the code base. But then other things came up as I was working that could get independently resolved, and once merged the diff would be clear.